The invention concerns a process for the production of a multi-layer body having at least one partially shaped functional layer in register relationship with at least one further partially shaped layer, and a multi-layer body which can be obtained in accordance therewith. The invention further concerns in particular a security element for security documents and value-bearing documents having such a multi-layer body.
Optical security elements are frequently used to make it difficult to copy and misuse documents or products and as far as possible to prevent such copying and misuse. Thus optical security elements are frequently employed for safeguarding documents, bank notes, credit cards, cash cards, identity cards and passes, packagings and the like. It is known in that respect to use optically variable elements which cannot be duplicated with conventional copying processes. It is also known to provide security elements with a structured metal layer in the form of a text, logo or other pattern.
The production of a structured metal layer from a metal layer which is applied over an area for example by sputtering requires a plurality of procedures, in particular if fine structures are to be produced, which have a high degree of forgery-proof nature. Thus it is known for example for a metal layer which is applied over the full surface area involved to be partially demetallized by positive/negative etching or by laser ablation, and thus to be structured. As an alternative thereto it is possible for metal layers to be already applied in structured form to a carrier by means of the use of vapor deposition masks.
The greater the number of production steps afforded for production of the security element, the correspondingly greater is the significance in terms of register accuracy of the individual process steps or the degree of accuracy of positioning of the individual tools when forming the security element in relation to features or structures already present on the security element.
GB 2 136 352 A describes a production process for the production of a sealing film provided with a hologram as a security feature. In that case a plastic film is metallized over its full surface area after the embossing of a diffractive relief structure and then demetallized in region-wise fashion in accurate register relationship with the embossed diffractive relief structure. The demetallization operation in accurate register relationship is costly and the degree of resolution which can be attained is limited by the adjustment tolerances and the procedure employed.
EP 0 537 439 B2 describes processes for the production of a security element with filigree patterns. The patterns are formed from diffractive structures covered with a metal layer and are surrounded by transparent regions in which the metal layer is removed. It is provided that the contour of the filigree pattern is introduced in the form of a recess into a metal-coated carrier material, in that case at the same time the bottom of the recesses is provided with the diffractive structures and then the recesses are filled with a protective lacquer. Excess protective lacquer is to be removed by means of a scraper blade. After application of the protective lacquer the metal layer is removed by etching in the unprotected regions.